The West Indies ended the day 14 runs ahead and, as they have to bat last on a pitch already showing signs of wear after two cloudless days of sunshine, they face an enormous challenge simply to remain in contention.
Among McGrath's victims was Brian Lara for the fourth time in five innings in the series, a sequence that prompted the bowler's not unrealistic assessment afterwards that he had got the celebrated left-hander's measure.
Lara was caught at second slip for two, cutting at the 18th ball he faced. It was the third successive time he had fallen for a single figure score to McGrath, and was a significant handicap to the West Indies' suspect batting that had demoted him in the order to No 4 in the hope that he would have the cushion of a reasonable start to regain lost touch.
"The answer is to keep it tight at him," McGrath said. "He likes to play his shots and he'll give you a chance."
From over the wicket or round, that has been the Australian plan to Lara since the 1995 series in the Caribbean, when they regained the Frank Worrell Trophy after 18 years in West Indies' possession. In his last 11 innings against Australia, Lara has managed only one half-century.
McGrath's efforts made up for the loss of his fellow paceman, Jason Gillespie, who strained a side muscle during his second over yesterday. He will not bowl again in this Test and is doubtful for his hometown Test in Adelaide on 25 January.
The pattern for the day was established in the first hour when the overnight pair, the left-handers Robert Samuels and Shivnarine Chanderpaul, were restricted by the miserly bowling and sharp fielding to 21 runs off 15 overs.
Samuels managed only two scoring strokes from his 57 balls before he edged his drive off Shane Warne to be smartly taken, low to his left at slip, by Mark Taylor.
Lara followed five minutes before lunch and, when Carl Hooper ran himself out soon afterwards and Chanderpaul's untroubled but pedestrian 58 was ended after three and a half hours by McGrath's left-handed return catch, the West Indies were tottering at 107 for 5.
It took a cricketer of no particular repute but a wholehearted, uncomplicated attitude to free them from their self-imposed shackles, but Junior Murray's brave counter-attack and his partnership of 90 for the sixth wicket with Jimmy Adams came too late for a complete revival.
Murray, back in place of Courtney Browne for the first time in a Test since the series against England in the summer of 1995, immediately stamped his authority on proceedings, crashing an off-driven boundary off McGrath as fiercely as any ball was struck in the innings and hoisting Warne over long-on for another four.
Boosted by his swashbuckling 86 in the World Series one-day international against Pakistan last week, Murray attacked with the same positive effect and, with Adams his steady partner, soon put bowling and fielding that had seemed so restraining into perspective.
He came unstuck against the second new ball when his compulsion to hook led to his dismissal from a top-edged stroke that was caught at long leg off McGrath.
Adams remained to the end, unbeaten 54 after a dogged vigil of three and three-quarter hours but others kept falling and Australia ended the day in the happier position.
Second day; Australia won toss
AUSTRALIA - First Innings 219 (G S Blewett 62; C E L Ambrose 5-55).
WEST INDIES - First Innings
(Overnight 29 for 1)
R G Samuels c Taylor b Warne 17
S Chanderpaul c and b McGrath 58
B C Lara c Warne b McGrath 2
C L Hooper run out 7
J C Adams not out 54
J R Murray c Reiffel b McGrath 53
I R Bishop lbw b McGrath 0
C E L Ambrose b Warne 8
K C G Benjamin b Reiffel 11
*C A Walsh not out 2
Extras (lb7 b4 nb3) 14
Total (for 9, 103 overs) 233
Fall (cont): 2-62, 3-71, 4-86, 5-107, 6-197, 7-197, 8-215, 9-230.
Bowling: McGrath 27-10-40-5; Reiffel 29-8-76-1 (nb3); Warne 25-3-60-2; Gillespie 3-2-5-0; Blewett 9-3-19-0; S R Waugh 10-5-22-0.
Umpires: S Venkataraghavan (India) and P Parker (Aus).Reuse content